Estes Airborne Surveillance Missile Build, #0867, Part 6, Dowel Trim

Before cutting the dowel, give it a shot of filler/primer and smooth sanding. You won't be able to sand the inside edges of the dowel after it is glued on the model. 

The low end of the dowel pieces sits on the top of the 5/20 ring.

On the left is the dowel end cut straight. I sanded the end at an angle for a better fit, shown on the right.

To keep track of the dowel end angles, 

Mark a pencil line down the outside of the dowel.

The upper end of the dowel is cut just a little long. When glued in place it should extend over the top of the ring.

After the glue dries, 

Carefully shave the top even with the upper face of the ring.

Be sure the knife blade is sharp and held flat so you don't cut into the cardstock ring.